Resputtered copper seed layer

Abstract

The present invention discloses a comprehensive copper deposition process, particularly suitable for forming a copper seed layer in narrow through-hole features prior to electrochemical copper plating, which process includes copper sputter deposition (160) followed by At least one cycle of the step of sputter etching (162) of the deposited copper is preferably performed in the same sputter chamber. This deposition is performed under conditions that promote a high copper ionization fraction and a strong wafer bias, thereby drawing copper ions into the through-hole features. The etching can be done using argon ions, preferably inductively excited by RF coils around the chamber, or by copper ions formed at high target power and strong magnetrons or by using RF coils. Two or more deposition / etch cycles can be performed. The final flash deposition (168) can be performed under conditions of high copper ionization and low wafer bias.

Description

technical field [0001] The present invention relates generally to sputter deposition in the formation of semiconductor integrated circuits. More specifically, the present invention relates to the combination of sputter deposition and sputter etching in forming a liner layer. Background technique [0002] Magnetron sputtering has long been used in the deposition of horizontally extended layers of metallizations such as aluminum and copper. More recently, magnetron sputtering has been adapted for the more challenging task of depositing liner layers in high aspect ratio holes such as interlayer electrical contacts, ie vias. Via features 10 for copper metallization shown in the cross-sectional view of FIG. 1 are formed over conductive features 12 on the surface of a lower dielectric layer 14 . An upper dielectric layer 16 is deposited over the lower dielectric layer 14 and its conductive features 12 , and vias 18 are etched through the upper dielectric layer 16 to the conducti...

AI Technical Summary

Problems solved by technology

Conventional copper seed sputter deposition is difficult to reach those concave grooves 64 and 66

[0012] The sputter deposition of the copper seed layer does not completely coat the sidewalls 54 of the recess or the sides of the grooves 64, 66, causing the same problems as described above with respect to the protrusions

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